Presented at AMS Conference 12th International Conference on Interactive Information and Processing System (IIPS) for Meteorology, Oceanography, and Hydrology
Atlanta, Georgia
January 28-February 2, 1996

The Implementation of an Interactive River Forecast System
for the National Weather Service

1. INTRODUCTION

The National Weather Service River Forecast System (NWSRFS)
has been used
by NWS River Forecast Centers (RFC) since 1985 to provide daily
river and
flood forecasts for major rivers and streams throughout the
United States. In
preparation for one part of NWS modernization, the
Advanced Weather
Interactive Processing System (AWIPS)
, the NWS Office of Hydrology (OH) has
ported the NWSRFS from the current mainframe environment to a
network of UNIX
based scientific workstations.

In addition, OH has developed the Interactive Forecast
Program (IFP) - a
graphical user interface to the operational forecasting portion
of NWSRFS.
The IFP allows forecasters to control the NWSRFS program flow and
to interact
with a graphical display of model results to easily make
necessary adjustments
to help produce more accurate and timely forecasts. The first
version of IFP
was described by Page (1991) and has undergone major changes and
enhancements
since then.

The NWSRFS and IFP, along with other RFC hydrometerology applications developed
for AWIPS, are currently implemented at most RFCs. This paper discusses their
current implementation and the interaction of NWSRFS and IFP with some of
these applications developed for AWIPS. Plans for further integration of NWSRFS
and IFP into the evolving AWIPS environment are also presented along with
their planned interaction with the Weather Forecast Office (WFO) Hydrologic
Forecast System (WHFS) currently under development and testing.

2. BACKGROUND

The mission of the
NWS
includes providing river and flood forecasts and
warnings for the protection of life and property and providing
basic
hydrologic forecast information for environmental and economic
well being.
The major responsibility for forecasting the Nation's major
rivers and streams
belongs to the NWS River Forecast Centers whose areas of
responsibility cover
the coterminous U.S. and Alaska. The RFCs pass their forecast
guidance to the
local Weather Forecast Offices (WFO). These WFOs are responsible
for issuing
all public forecasts for weather and hydrology. The areas of
responsibility
for these offices are shown in Figure 1.

Figure 1. RFC and WFO areas of responsibility.

3. PRE-AWIPS IMPLEMENTATION

The primary tool for producing the river forecasts at RFCs
is the NWSRFS.
The major components of a river forecast system are represented
simply in
Figure 2. There is a component to store and retrieve data, one
to process the
data into a form that can be used by the hydrologic models, one
to perform the
scientific calculations, and one to handle the output of the
Figure 2.
Functions of a river forecast system.

Figure 2. Models that represent the current and projected states
of the river flow.

These functions have been
available in NWSRFS in a mainframe environment at the NOAA
Central Computing
Facility (NCCF) since 1985. NWSRFS functions are run by sending
command input
over Remote Job Entry (RJE) lines to the NCCF. Line printer
results are sent
back to the RFC for display on standard printers or on text
display screens.
In the pre-AWIPS implementation of NWSRFS now available at most
RFCs, a
network of UNIX based scientific workstations allows the RFCs to
do these
functions locally (Figure 3).

Figure 3. Pre-AWIPS workstation network.

3.1 Data

Hydrologic modeling for streamflow and water resources
forecasting
depends on real-time data of the current and projected
conditions. In the
pre-AWIPS implementation, data from many different sources are
collected and
stored in a relational database management system (RDBMS). These
sources
include the modernized data sources of
WSR-88D
radar precipitation and the
Automated Surface Observing Systems (ASOS)
currently being installed. NWSRFS,
as ported from the mainframe, has its own database based on flat
files. The
raw data is transferred from the RDBMS to the NWSRFS database by
processes
that also do some basic quality control.

3.2 Processing

Once the data is in the NWSRFS database it must be processed
into a form
that can be used by the hydrologic models. In NWSRFS, all data
is passed
between hydrologic models in time series
format. This requires that all the raw
data, which may have missing values and
values gathered at different time
intervals, be processed into regular time
series.
There are several preprocessors in the
Operational Forecast System (OFS) component
of NWSRFS that perform this function. In
general, they take the raw data that is
unevenly distributed in time and space,
make estimates for missing data (where
appropriate) based data on from surrounding
stations, and time distribute the data.
Many of the preprocessors also compute an
areal average for the forecast watershed basins. OFS
preprocessors include
Mean Areal Precipitation based on precipitation gage estimates,
Mean Areal
Temperature, Mean Areal Potential Evaporation, and one to handle
non-areal
averaged data such as river, reservoir and snow data.

A recent addition to the preprocessors was one that
calculates Mean Areal
Precipitation based on WSR-88D radar precipitation estimates.
This
preprocessor uses the output of the StageIII Precipitation
Processing Program,
another of the
modernized RFC
applications, as
its input. The use
of the WSR-88D data
for precipitation
processing is
described by Shedd
and Fulton (1993).

The
preprocessors are
run automatically
throughout the day
as new data becomes
available to update
the input time
series used for forecasting. The
preprocessors are run as automated jobs requiring no user
interaction.

3.3 Modeling

NWSRFS was designed to be a modular system that contains a
variety of
models and procedures and allows the user to control the
selection of models
and their order of use in a basin. In NWSRFS, the functions
representing one
scientific algorithm, such as a snow, soil moisture, or river
routing model,
are called an operation. An operation is a set of functions that
performs
actions on a time series. Generally, an operation describes the
equations of
motion governing the flow of water through a portion of the
hydrologic cycle.
There are also operations to display results or to perform
utility functions
such as adding two time series. Details on the design,
development, and
structure of NWSRFS can be found in Smith and Page (1993) and
Page and Smith
(1993).

Designers of NWSRFS realized that forecasting was inherently
an
interactive process because the models did not simulate the water
movement
perfectly, the calibration parameter values for the models do not
produce
perfect results, and the input rainfall, temperature,
evaporation, and stream
condition
data were not perfect. Creating an effective interactive
environment on the
mainframe was a difficult task. Beginning in 1989, the OH began
a project to
prepare for the AWIPS local processing environment. The
computational and
graphical capabilities of the scientific workstations led to the
development
of the Interactive Forecast Program (IFP).

In the operational pre-AWIPS setting, the IFP allows
forecasters two
major advantages over the mainframe environment. First is the
ability to
control the forecast run and to view the output much faster and
easier than on
the mainframe. The model output displays in IFP on the
workstation are
graphical and color coded rather than text file output which
makes it easier
for the forecaster to read and analyze.

The second major enhancement IFP brings is the ability to
easily create
the run-time modifications to correct bad data values, change
certain model
state variables, etc. to improve the forecast simulations. The
mechanism for
making these modifications is a feature of OFS. In the mainframe
environment,
typing in the command input, sending it through RJE, and waiting
for the line
printer output to see the results often took too long to do many
iterations in
a forecast cycle. With IFP, modifications are made with mouse
interactions on the graphical displays and the hydrologic models
are rerun at the
click of a button so results of
changes can be displayed in seconds.
The RFC forecaster can concentrate
on the scientific basis of the
proposed modifications, not the
mechanics of typing in changes. The
better the forecaster can identify
and correct the sources of error in
the simulations, the more model
state variables will reflect the
current conditions. For well
calibrated basins, this translates
into better forecasts.

As currently implemented in the
pre-AWIPS environment, the forecast
program that actually performs the
river forecasting computations can
be run through a batch run or
through IFP. Either way, run-time
modifications made through IFP are
incorporated into the forecasts.

Other NWSRFS/OFS programs allow
forecasters to specify the
characteristics of the data stations
and to configure the basins,
choosing the models to be run and
the parameters needed for them.
These programs are run in batch mode
and all the parametric information
is currently stored in the NWSRFS
database. All time series that
result from the preprocessors and
those used in the forecast component
of OFS are also stored in the NWSRFS
database.

3.4 Output

As mentioned earlier, in the
NWS, the responsibility for
producing the public forecast
products is reserved for the local
WFO. Therefore, the RFCs must get
their river forecast information to
the WFOs in their area of
responsibility.

In the mainframe environment,
the production of the river guidance
products requires that the
forecaster pick off the values from
the printed output, type in the
message, and send it to the current
NWS communications network - AFOS
(Automated Field Operations and
Services).

In the pre-AWIPS workstation implementation, the preparation of river forecast
information is automated with the interactive Standard Hydrologic Exchange
Format (SHEF) Encoded Time Series program (SETS) which was developed at the
Arkansas-Red Basin River Forecast Center . SETS allows the forecaster to choose
the forecast points for which to produce the river information. Either daily
or flood forecasts can be generated. SETS retrieves the latest observed data
from the RDBMS and the forecast time series data from the OFS database. These
data are formatted into a SHEF forecast product. The forecaster then has the
opportunity to edit the message to add additional information if needed. The
forecasts are then sent via AFOS to the WFOs.

4. PLANS FOR AWIPS IMPLEMENTATION

One of the major components of
the modernization of the NWS is the
Advanced Weather Interactive
Processing System (AWIPS). This
system will provide a local network
of UNIX based scientific
workstations to all RFCs and WFOs.
It will also provide a state-of-the-
art communications network
connecting all NWS offices to
replace the current overloaded AFOS
network. Finally, it will provide
(1) a common database structure to
hold all observed, forecast, and
parametric data needed for
forecasting weather and streamflow,
(2) tools to assist in the
development of local applications,
and (3) a common user interface
environment consisting of
interactive forecasting tools for
RFCs and WFOs.

4.1 NWSRFS and IFP Integration into
AWIPS

The NWSRFS and IFP are two of
the major RFC applications that will
be included in AWIPS. In order to
fully integrate them into AWIPS,
they are undergoing some changes.
NWSRFS, in its current
implementation, has its own custom
database for the observed,
processed, and parametric data. The
AWIPS database will be designed to
store all of these data in a more
standard RDBMS. As a result, the
NWSRFS database access routines are
being rewritten to be able to read
and write to the AWIPS database.

The IFP uses the same database
access routines as NWSRFS so IFP
will also be able to read and write
to the AWIPS database. In addition,
AWIPS applications are designed to
have a similar graphical user
interface and be integrated into a
common framework. This is to help
forecasters easily move between
applications needed to produce their
forecasts and maintain the system.
IFP was written before there was an
AWIPS framework, therefore, for full
integration into AWIPS, IFP will be
ported to the AWIPS structure as it
becomes available.

4.2 RFC-WFO Interaction in AWIPS

In the modernized NWS, the hydrologic services program will rely on a much
closer coordination between the RFCs and WFOs for hydrologic data and products.
NWSRFS has been available to RFCs since 1985 but there has been no similar
forecast system available at all WFOs. Several different modeling tools have
been in use at different WFOs. The OH is currently developing and testing
a WFO Hydrologic Forecast System (WHFS) (Shelton and May, 1996) that is designed
for use by all WFOs in AWIPS.

WHFS currently includes an
integrated environment which
provides a database maintenance
tool, a data viewer application, a
system for modeling flash flood
areas, and an application for
automatically generating the public
hydrologic forecast products. The
system is currently being tested at
a several sites.

Two of the applications in the
WHFS are designed so that they can
also be used at an RFC. The first
is the database maintenance tool,
Hydrobase, which allows forecasters
to easily look at and update the
static data stored in the RDBMS such
as station, flood stage, and rating
curve information. The second is
the HydroView application which
allows forecasters to graphically
display observed and forecast data
fore all stations and forecast
points in the area of
responsibility. Since the same information is
needed at both the WFO and RFC it
makes sense that they both utilize
the same applications to view and
update data. The major difference
will be that the RFC database will
contain information from all the
WFOs in their area. Also, the RFC
and WFO will have a common database
structure so an update to
information in one database can
trigger an update in the other. An
example of this would be adding a
new station to the database. The
service hydrologist at the WFO would
enter the information in the WFO
database and it would automatically
be added to the RFC database and
available for use. This reduces the
effort required at the two sites to
keep their data updated and
eliminate the possibility of
different sites using different
data.

The ability to update other
databases is important when
considering the close coordination
needed for the forecast modeling
system in WHFS. In addition to
disseminating the normal RFC river
and flood forecasts to the public,
WFO s have the responsibility for
producing hydrologic forecasts for
flash flood areas.

The modeling system in WHFS is
based on NWSRFS. It will be the
responsibility of the RFC to make
runs for these areas at least once a
day and to transfer the values of
the state variables of the models to
the WFO database so model runs at
the WFO will have the most current
conditions. In addition, the RFCs
will assist in model calibration for
these areas and transfer the
parameter values to the WFO. This
cooperation is possible because the
RFC and WFO will be able to use the
same hydrologic models.

Finally, the river forecast
guidance products will be generated
at the RFC in a manner similar to
the pre-AWIPS implementation, using
SETS. These will be sent to the
WFOs where the river product
formatter component of WHFS,
RiverPro, will use the time series
information to produce and
disseminate the final public river
or flood forecast.

5. CONCLUSIONS

AWIPS is scheduled to begin
installations in late 1996 and be
fully deployed to all NWS offices by
early 1999. Until then, the pre-
AWIPS implementations of NWSRFS and
IFP and other RFC applications will
be used at the RFCs. In addition,
work will continue to port these
applications into the evolving AWIPS
environment and to integrate them
with the WHFS. The AWIPS
environment will allow all current
and future hydrologic forecasting
applications to be more consistent
and better coordinated and improve
the hydrologic services provided by
the NWS.

Page, D., and G.F. Smith, 1993: National Weather Service
operational river forecasting in a UNIX environment.
Engineering Hydrology: Edited by Kuo, C.Y., ASCE, 838-843.
Shedd, R.C. and R.A. Fulton, 1993: WSR-88D Precipitation
processing and its use in National Weather Service
hydrologic forecasting. Proceedings of the International
Symposium on
Engineering Hydrology, San Francisco, CA, ASCE, July 25-30, 1993.